Asphalt roofing composition



United States Patent Ofifice 2,859,125 Patented Nov. 4,

ASPHALT ROOFING COMPOSITION RalphrR. Uhrmacher, Fort Worth, Tex., assignor to Panther Oil '& Grease Mfg. Company, Fort Worth, Tex., a corporation of Texas No Drawing. Application May '27, 1957 Serial No. 661,588

' 3 Claims ((31,106-278 able solvent to form a Weatherproof coating when spread on roofing felt.

. This application is a continuation-impart of my co-.

pending application Serial No. 469,315, filed November 16,, 1954, now abandoned.

It'is common practice to apply anasphalt coating to roofing felt at the time a roof is built or when its Weatherproofing quality becomes impaired. Heretofore such coatings have comprised air-blown asphalts thinned with apppropriate solvents to provide the desired viscosity. Air-blown asphalts contain traces of minerals such as vanadium, magnesium, calcium and nickel, which apparently act in the same fashion as paint driers, and cause the asphalt solution to rapidly form'a skin on the exposed surface of the coating when it is spread, as on a roof.- Thisskin represents an advanced stage in the formation of a gel and contains less solvent and a larger amount of Oxygen than the rest of the coating.

The tackiness, or adhesive quality, of the roofing com position "is of'particular importance in the weatherproofing-of a new roof, or of an old roof, when an additional layer of roofing felt is to be applied on top of a layer of the roofing composition. Therelative dryness of the skin formed on the exposed surface of compositions containing air-blown asphalt, when such compositions are spread on a roof and exposed to air, does not provide the adhesive qualities desirable for'the application of an additional layer of roofing felt. Accordingly, when an additional layer of roofing felt is to be applied on top of a coating of; such composition, it is necessary to limit the application'of the asphalt coating to a comparatively small area of the roof, so that the coating will not become too dry for the additional-layer of roofing felt to be cemented thereto. Such piece-meal application of the roofing composition substantially increases the time, and consequently the expense, of weather-proofing a roof.

The skin-formed on the exposed'surface of roofing compositions of air-blown asphalt also prevents the composition from curing uniformly, and thus' causes the'forma tion of alligatored surfaces containing high and low spots, eventhough the compositionis, spread evenly when it is applied. 'The' euring'of coatings of such 'composi- 1 tion induces a strain in the coating which tends to break the coating at the margin of the high spots, thereby causing premature failure of the weatherproofing qualities of the composition, as evidenced by leaks through the roof to which the composition is applied.

Another disadvantage incidental to the use of air blown asphalt as the base of roofing compositions is the fact that efficient protection of the roof is impossible if the presentinvention is concerned-the asphalt provides the protective covering, and the solvent is merely the carrier that facilitates the .application of the asphalt to the roof. In order for the asphalt to be spread properly the composition must havea certain viscosity, namely within the range of between 200 and 250 seconds on the Saybolt Furol orifice. at 122? F.. In order to-attain the required viscosity roofing compositions having air blown asphalt as a base must have at least 35%. solvent by weight. Ac cordingly, the maximum asphaltcontent of the composition is 65% by weight.

It is obvious that any increase in the percentage of asphalt in roofing compositions would increase the efiiciency of the composition and'lower the cost of weatherproofing the roof because it would-reduce the amount of solvent required.- Heretofore' attempts to increase the asphalt content in roofing compositions having an air blown asphalt base have resulted in gelled materials that cannot be used as roofing compositionsr Since catalytically blown asphalt has a'lower viscosity than air blown asphalt it would appear that the substitution of catalytically blown asphalt for air blown-asphalt would enablethe use of a greater percentage of asphalt in a composition having the required viscosity. It has been found however that .the solvents used for air blown asphalt are not suitable for use as solvents for catalytically blown asphalt .becausesuch compositionsform a gel after a short period of time.

cal unions with the traces of metals found in air-blown The particular typev of solvent to be used depends upon the ultimate use'of the composition. For example, it has been found that if a petroleum distillate such as varnish makers and painters naphtha is used alone as the solvent, the composition forms a gel after a short makes it possible to keep the catalytically blown asphalt.

" in solution for prolonged periods of time.

roof is wet when the composition is applied. The skin a which forms on the exposed surface entraps any moisture present in the form of bubbles or blisters.

la roofing compositions of the type with which the In the preferred embodiment of my invention the. roofing composition contains approximately 70% catalytically. blown asphalt and- 30% solvent by weight. Ordinarily the. tolerance .is-.within 1%, and the asphalt content is.always at least 65% by weight. The solvent consists of a blend of two thirds petroleum solvent and one third aromatic solvent. 1

The petroleum solvent'may be a varnish makerisian'd,

painters type of naphtha. Preferably the naphtha is raw or-unsweetened, because of its greater economy.

The unsweetened solvent ,hasa small sulfur content,' sinc'ej sulfur. is a normal-,c'ontamin'antof petroleum-products; and the sulfur improves thesolvency of the naphtha.

Lbsigal. F" Flash F. (Tag)-.. 149 Kauri-butanol (1) 95 Aniline ,-point,,mixed F-- 77 Percentaromatics L. 8320 Color, Saybolt 19 Distillation, F.-:

IEP 346 off 405 50% off 458 90% ofi 5G6 FBP 537 The blend of aromatic solvent andpetroleumnaphtha possess the followingdistillation characteristics:

Petroleum fractions having a high content of aromatic hydro-carbon also constitute desirable solvents. Although hydro-carbon solvents are preferred, it is possible touse chlorine-containing organic compounds, such as, for example, orthodichlorobenzene, monochlorobenzene, ethylenechloride, and carbon tetrachloride. It is also possible to'use sulphur-containing organic compounds, such as phenyl mercaptan, thiophene, or some of the aromatic sulphides. Another solvent that might be used is a nitrogen-containing organic compound, such as aniline. The. chlorine, sulphurand nitrogen-containin'gprganic compounds are not generally used. as solvents for commercial preparation of'roofing c'ompositions because theylare too expensive, compared to themorecommon hydro-carbons; Carbon disulfidel is another very efficient solvent, but is not 'recommendedbe cause of its" extreme volatility and firehazards- The viscosity of my' roofing "composition is 'withinfthe I range of 200m 250 seconds on the Saybolt'Furol orifice alligatored surface.

to evaporate freely and tomaintain-the open surface L until the roofing material is completely cured.

The open surface on my composition also makes 'it I possible to apply the roofing composition on wet roofs' because it will adhere to wet surfaces and will penetrate I such surfaces as the moisture is driven out by the action of the compositionas well as by natural drying. The composition does not form a skin on the'exposedsurfacie,

and-the moisture cannot be entrapped.- As the-moisture is driven out of the roof the composition penetrates ithe voids left by the removal of such moisture and prevents a subsequent access to the roof by waterfrom rain or any" other source.

The curing is uniform throughout the spread SbhltiOIlgi' and the uniform drying characteristic of my composition prolongs the eflective time 'during which an additional;

layer of feltmay be cemented tothe asphalt coating The longer period of time during which the asphalt coat ing presents an open, sticky surface; permits larger area of roofing to be covered with a single application of the roofing composition .before the 'additional layer of fe ltff must be applied. V

The uniform curing of my asphalt coating also provides a coating of uniform thickness when'the asphalt composition is spread evenly, and prevents the formation ofian V The absence of high and lowspots' in the surface of my coating eliminates the possibility of' ati122 F. andjmay be brushed readily. .In applying the solution'to' a roof it is customary -to nail ajlayer of roofing'feltin place. Azcoating of'the roofing composi tion is 'then spread overthe felt, and another layer of felt is 'applied'over the firstlayer. It is important that the roofing composition quickly develop tackiness and adhesive qualities to cement the; second layer offelt ,in place; 'My compositiorr'of catalytically blown asphalt in anappropriate,solvent'does not produce "a skin, and therefore presents an .open' surface throughout the area over .vi'lliichit'ifs'spread, thereby permitting the solvent early failure of the weatherproo'fing quality of thecoatingl due to breaks in the surface'caused by strain'induc'ed by 1 such .high and low spots.

While I havedescribed a few preferred-embodiments' of my invention 'in-detail, it will beu'nderstood that-'the description thereof is 1 illustrative rather than restnjenve;

as many details may be'modified or changed without de parting from the spirit or scope of myinventionr Ac-* cordingly, I'do not desire to be restricted to1the exact-l '1 composition described, except as limited by the appended,

claims.

I claim: 1. A roofing composition consisting of anyasphalt blown in the presence of phosphorus pentoxide anda-fsolvent comprising a mixture of xylene and petrole'pm naphtha. V

2. A roofing'composition consisting of an asphaltblown in the presence of a phosphorus catalyst and .a solventfj comprising a mixture of alkyl benzene and petroleumof aphosphorus catalyst and from 25 "to 35'% -of a solvent} said solvent consisting of a lower alkyl benzene and petro leunr naphtha in approximately a" one to tworatia: o

References Cited'in the'file ofthis patent UNITED STATES PATENTS 2,086,968 Stafford July 13, 1937 2,427,848 Garrison Sept. 23,1941 2,450,756 Hoilberg Oct. 5,1948 2,649,384 Anderson Aug. 18, 1953] FOREIGN PATENTS V 640,055 Great Britain JuIy 12, 19501 onsistingessentially ofifroni? V to -%'by weight of an asphalt blown inthe presence 

1. A ROOFING COMPOSITION CONSITING OF AN ASPHALT BLOWN IN THE PRESENCE OF PHOSPHORUS PENTOXIDE AND A SOLVENT COMPRISING A MIXTURE OF XYLENE AND PETROLEUM NAPHTHA. 